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OpenTimestamps

OpenTimestamps is a hash-based timestamping system that aggregates commitments and anchors them to Bitcoin. A client can retain a proof that can later be resolved to a Bitcoin transaction and checked against the chain.

What it does well

  • It offers a clear route from a document hash to evidence anchored in a public blockchain.
  • It keeps document bytes out of the timestamp request.
  • It is a strong fit for users who want the long-term trust story to center on a public chain rather than a particular timestamp operator.

Trust, privacy, and operational model

Long-term integrity depends on the Bitcoin chain and its consensus assumptions. Calendar services provide submission and aggregation, so availability and proof completion still involve service operations. Hash-only submission does not make predictable or public content secret, and network metadata remains outside the proof's privacy properties.

The workflow generally separates quick submission from later blockchain anchoring. Confirmation time, chain availability, and any applicable fees are part of the operational model.

Difference from Witness

Witness returns a threshold-signed attestation from configured witness nodes and can later add RFC 9162 batch proofs, federation cross-anchors, and optional external anchors. Its fast result relies on enough independent witnesses not colluding; OpenTimestamps places its primary durability claim on Bitcoin. These are different trust choices, not a ranking of systems.

When to use it instead

Use OpenTimestamps when a public-chain-derived proof and reduced reliance on a timestamp federation matter more than immediate quorum evidence or operating a Witness network.